Characteristics of Chang 2 Low Resistivity Pay Zones and Petroleum Geological Significance in Zhidan Area,Ordos Basin
The resistivity of the Chang 2 oil layer is generally low in the Yanchang Formation of the Zhidan area,Ordos Basin,making it difficult to identify the oil layers,and it has been viewed as a non-main development oil layer for a long time.Focusing on the difficulties of well-logging identification in low resistivity oil layers,the influence of typical characteristics of formation water salini-ty,microscopic pore structure,rock mineral composition on the reduction of reservoir resistivity through comprehensive processing of core,formation water,casting sheet,clay mineral,well-logging curves,production performance and other data was analyzed,and the petroleum geological significance of exploration and development in the study area was discussed.The results show that under the sedi-mentary environment of delta plain subfacies,Chang 2 oil layer is dominated by medium-fine-grained feldspar sandstone,and the pore structure is extremely complex due to the strong compaction.The high salinity of formation water in the Zhidan area,accompanied by complex microscopic pore structure and strong additional conductivity of clay mineral,which leads to the free conductive network formed by fluid and rock being the internal reason for the low resistivity of pay zones.Chang 2 low resistivity pay zones are kind of sub-tle oil layers with great potential for exploration and development,so combining the cross-plots with the comparison results of adjacent water layers can effectively improve the accuracy of well-logging identification.It is suggested that more attention to the analyses of low resistivity causes and the identification of the Chang 2 oil layer in the Yanchang Formation,so as to provide a theoretical basis for stabi-lizing production and tapping the potential of the old oil areas in the Yanchang oilfield.
low resistivity pay zonesformation water salinitylogging responseapparent resistivity increasing rateZhidan area
万方数据
维普
